Walking boot for diabetic and other patients

ABSTRACT

An orthopedic walking boot promotes rapid healing of diabetic foot ulcerations by lowering the maximum peak pressure imposed upon the foot. The walker has a hard unyielding shell which is designed for walking. The shell closely and rigidly supports a mid-sole in a foot-shaped bed. The mid-sole has a foot-shaped cavity with rounded sides adapted to form resilient support for the heel, arch and sides of a foot in addition to the bottom of a foot. A conformable inner-sole is adapted to fit over the foot-shaped cavity in the mid-sole and be compressed in response to foot pressure between the sides and bottom of the foot and the sides and bottom of the foot-shaped cavity in the mid-sole thereby compensating for small differences between the shape of the foot and the shape of the cavity. Weight applied to the foot is transferred to the walking shell by contact between the sides of the foot, arch, and heel and the arch, heel and sides of the foot-shaped cavity as well as the bottom of the cavity thereby decreasing the peak or maximum unit pressure on the plantar surface of the foot. A breathable bootie which wraps the foot and lower leg in a protective “cocoon” is preferably secured to the upper surface of the insole thereby preventing foreign materials from entering the foot cavity.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates generally to orthopedic devices,and more particularly to an orthotic support for assisting in thestabilization and proper healing of ulcerative or pre-ulcerativeconditions, plantar fasciitis or other conditions of the foot,especially for diabetic patients.

[0003] 2. Background of the Invention

[0004] The present invention relates to orthotic or orthopedic devicesthat are used to immobilize, support and brace the foot and ankle. Thesole or plantar surface of the foot is often subject to conditions orinjuries, such as stone bruises, heel spurs, soft tissue injuries orinjuries of the muscles, ligaments, bones or joints. Foot problems ofthis kind are often painful and exacerbated by the patient's need towalk during the healing process. The degree of immobilization andprotection required varies with the severity and difficulty of thecondition. Relief may sometimes be obtained by use of a moldedinner-sole or orthotic pieces in a regular shoe to add stiffness oralter the pressure distribution on the foot. Another option is custommade shoes which, although expensive, may provide relief for minorconditions. These may be augmented with the use of ankle braces orcrutches but provide little relief for more serious conditions.

[0005] Diabetics are subject to especially severe and difficult footproblems. As the condition of diabetes gets worse, these patients beginto develop a problem called neuropathy, or polyneuropathy where theylose the sense of feeling in the plantar surface or bottom of the footwhich may extend from the toes up the foot to the heel and eventually upto the lower leg or higher. Because there is no feeling, these patientsare subject to severe pressure induced ulcerations which can be causedby high peak pressures, or by hard foreign particles that may get intheir shoe which they do not realize are present. This often results inulceration of delicate skin, which in diabetic patients is often verydifficult to heal. Sometimes the festering ulcerations become infected,contain scar tissue and may result in secondary problems up to andincluding amputation. There were an estimated 54,000 amputations of thiskind done in the United States in 1998. There are an estimated 23million diabetics in the United States alone.

[0006] Prior art solutions have attempted to solve the problem byattempting to control the pressure on the bottom or sole of the foot.For example, a company called Royce Medical Company has modified theirordinary leg walker by replacing the normal Poron™ inner-sole with abouta ⅜ inch thick cross linked polyethylene foam inner-sole material knownas “plastazote” where the upper surface is cut into small hexagon shapesof roughly ⅜ inch across. One or more of the hexagonal areas directlyunder the ulceration or pressure site can be removed to create areduction in pressure at the ulcer site itself. This can sometimes causea distended wound because the exudate coming out of the ulcerated areacauses a distention of the ulcer site which eventually granulates in toform scar tissue that has to be shaved off to avoid high pressure inthat area when the foot is placed in a normal shoe. Removal of supportunder part of the sole of the foot tends to increase pressure loading ofremaining portions of the foot which are supported. Royce MedicalCompany is the owner of U.S. Pat. No. 5,464,385 entitled “Walker withOpen Heel”.

[0007] Another example of the prior art approach is the walker producedby a company called Aircast, known as the Aircast Diabetic Walker™. Tothe ordinary walker they install a layer of about ½ inch to ⅝ inch thickcross-linked polyethylene foam referred to in the industry as“plastazote” foam in the bottom of the walker. It is a flat materialwhich takes a compression set. While this does tend to distributepressure over more of the foot to some extent, the support is stillprovided mainly by the boney prominences of the foot where the heel andball of the foot fully compress the foam material. High unit pressure isfound in those areas. We describe this result as producing a parabolicpressure distribution curve with a very high peak right under the boneyareas.

[0008] Heretofore, the best available orthotic is a molded orthoticdevice which has been developed in the last several years using atechnique called Total Contact Casting. Typically, a dressing is appliedover the wound and then a piece of cotton or wool felt that will absorbexuding fluid is placed around the foot and held in place by acircularly knitted tubular material which is called a stockinet. Then,in one preferred method, a material called “conform”™ foam or “tempur”™foam is used next. Approximately a ½ inch layer of this is placed underthe arch and folded over the front of the toe down to the sides andpinched in on the sides creating somewhat of a cocoon below the anklebones from the bottom of the foot up and over the forefoot. Over the topof this is wrapped some padding material for the cast which is either acotton or polyester wool as is used for any other type of cast. Then afirst layer of plaster or synthetic material is placed over the foot toform the cast and a wooden board is placed under the foot. Another layerof plaster or synthetic casting is plastered over the whole thing thuscreating a “cocoon” for the foot. The “conform”™ foam or “tempur”™ foamhas an open granular structure which compresses easily and reboundsextremely slowly. It will not sustain the body's weight without going toessentially zero thickness. We believe the Total Contact Castnevertheless still produces a parabolic pressure distribution curveunder the boney portions of the foot. Unfortunately, the total contactcast is heavy and not well designed for walking. The user has to pickthe whole foot up and lay it down again, and it can only be used forabout a week before it has to be removed and the foot cleaned and a newcast applied. The weight and bulkiness of the total contact cast createadditional problems for diabetic patients. Patients can't remainimmobilized to keep their weight off the cast. It is necessary for themto do some walking. Walking is beneficial because it actually stimulatesthe healing process. As a result, diabetics will start developingproblems in other areas of their body because they are sensitive topressure. Their tissues will break down at about half of what a youngathlete can take without damage. The use of crutches can causeadditional ulcers under the arms or on the hands.

[0009] Modern medical theories suggest that there may be some thresholdunit pressure maximum if healing is to occur. If higher pressures areproduced in “hot” spots, healing may take an extended time or bedifficult to obtain at all. It appears that what might be called thetime-pressure integral may also play an important role. Thetime-pressure integral relates to the cumulative effect of activity bythe patient which produces pressures under all of the foot over a giventime period.

[0010] It would be desirable to have a walker which can be used over anextended period of time and which improves upon the attributes of thetotal contact cast by reducing the peak plantar pressure operating onthe injured foot while walking in the walker. We have demonstrated suchan improvement with a new approach that utilizes the arch and side areasof the periphery of the foot to support part of the load on the foot andreduce the maximum peak pressure under the sole of the foot.

SUMMARY OF THE INVENTION

[0011] The improved walking boot of the invention for diabetic and otherpatients reduces the maximum peak pressure applied to the bottom orplantar surface of the foot while standing or walking, as compared tothe best prior art orthopedic devices. The new walking boot is referredto as the Bledsoe Conformer Boot. The walking boot has a premoldedfoot-shaped cavity and an inner-sole made of conformable material whichis molded by foot pressure to the shape of the foot. It operates on theprinciple of preloading the arch and side edges of the foot to take andspread some of the weight load on the foot before the bottom of the footis fully loaded. Supporting pressure for the foot is spread over alarger area to reduce the peak unit pressure at any particular area.This is an improvement over flat-bed boots even though they may have acontoured surface and be made of a flexible or spongy material and havea compressible insole.

[0012] The improved walking boot has a walking shell having an innersurface with an upturned edge portion which forms an unyieldinggenerally foot-shaped bed adapted to support a mid-sole. The walkingshell has an upwardly angled forward portion which the tread follows toallow the boot to roll forward in a walking step. The rear portion ofthe heel on the tread is angled to improve walkability also. A mid-soleis supported and held in the generally foot-shaped bed of the walkingshell. The mid-sole is premolded to form a foot-shaped cavity withupwardly and outwardly rounded side edges to form a resilient butnon-compressively setting support for the arch and sides of the heel andfoot in addition to the bottom of the foot. Over the foot-shaped cavityof the mid-sole is placed a conformable inner-sole formed from a pliablebut compressibly settable material which is referred to as aself-molding material that takes the shape of the bottom portion of thefoot when the foot is pressed into the foot-shaped cavity. In responseto foot pressure between the sides, arch, and bottom of the foot and thesides, arch, and the bottom of the foot-shaped cavity in the mid-sole,the inner-sole conforms to the shape of the foot thereby compensatingfor small differences between the shape of the foot and the shape of thefoot-shaped cavity. Weight applied to the foot compresses and molds theconformable inner-sole to fit tightly between the heel, arch, and sidesof the foot and the sides and arch area of the cavity thereby preloadingthe foot along the heel, arch, and sides of the foot before the heel andball of the foot are fully loaded by compressing the inner-sole and themid-sole at the bottom of the cavity. The foot-shaped cavity in themid-sole has a foot-shaped opening near the size of a selected averagefoot. The size and shape of the foot-shaped cavity and the thickness ofthe conformable inner-sole are selected to assure that the foot ispreloaded along the sides and arch of the foot-shaped cavity before thefoot is fully loaded on the bottom of its heel and ball areas. The crosssectional thickness of the mid-sole and the highly loaded areas underthe heel and ball of the foot are selected to be a minimum thickness inorder to minimize leg height differential and any relative motiontending to be caused by compression of the mid-sole arising because ofperiodic compression of the mid-sole in response to foot loading whilewalking. Relative motion between the foot and the foot-shaped cavity isminimized to prevent any tendency for chaffing.

[0013] The walking shell has upwardly turned edges along the sides andheel areas which provide support to the outer lower surface of themid-sole to prevent any spreading of the mid-sole in response topressure from the weight of the patient. The upper surface of thefoot-bed and the lower outer surface of the mid-sole are closelyconforming so that unyielding support is provided by the rigid walkingshell.

[0014] The walking shell has a pair of upstanding struts which extendupwards on both sides of the leg, attached to the upturned edges of theshell which serve to secure the walking boot on the leg of the wearer.The walking boot further includes a durable and resilient softprotective bootie adapted for extending around the lower leg and footand having an open bottom portion having sides all around the foot and atoe box that are secured to the upper surface of the inner-sole to forma soft protective bootie around the foot and lower leg. Attached to eachof the struts is a sheath which is provided with patches of hook andloop material for the purpose of attaching the bootie to the shell. Thebootie also has appropriately located patches of hook and loop materialwhich together with encircling straps removably secure the structure tothe leg. The shell also contains straps together with hook and loopmaterial or other appropriate fastening means which hold the assemblysnugly on the foot.

[0015] The Bledsoe Conformer Boot is usable for the duration of theinjury and does not have to be replaced every five to seven days as doesthe Total Contact Cast. The conformable inner-sole comprises anelastomeric foam having a skinned outer surface to prevent penetrationby moisture, exudate or other liquids to which it might be exposed.Since these materials do not penetrate the inner-sole, the material issubject to washing and/or disinfecting if it is necessary to dress awound or ulcerated area. Unlike the Total Contact Cast which is fixed onthe lower leg and foot, the Bledsoe Conformer Boot is removable by thepatient, as for example, at bed time. It is truly a walker whichfacilitates walking because it has good walkability due to the shape ofthe floor contacting surfaces. The bootie is made from a soft breathablefoam material of about ¾ inch in thickness which together with theinsole provides a protective “cocoon” to prevent foreign materials fromentering the foot chamber.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016]FIG. 1 is a perspective view of the improved walking boot andbootie in the completely installed position;

[0017]FIG. 2 is an exploded perspective view showing the walking shell,mid-sole and construction of the bootie secured to the inner-sole of thewalker of FIG. 1;

[0018]FIG. 2A illustrates a preferred manner in which the bottom edge ofthe bootie can be attached to the inner sole;

[0019]FIG. 3A is a sectioned side elevation of the walker shell on thelines 3A-3A of FIG. 2 showing one of the upwardly extending struts onthe shell and fastening means which are used to secure the walker to thefoot;

[0020]FIG. 3B is a sectional elevational view of the walker shell ofFIG. 3A on the lines 3B-3B looking to the rear of the boot;

[0021]FIG. 4A is a plan view of the mid-sole which is supported directlyon its bottom surface by the inner surface of the walker shell;

[0022]FIG. 4B is a side elevation of the mid-sole of FIG. 4A;

[0023]FIG. 4C is a bottom view of the mid-sole of FIGS. 4A and 4B;

[0024]FIG. 4D is a section in side elevation of the mid-sole for thewalker shell of FIG. 4A-C along the lines 4D-4D of FIG. 4A;

[0025]FIG. 4E is a section in front elevation at the arch area of themid-sole of FIG. 4A-C on the along the lines 4E-4E of FIG. 4A;

[0026]FIG. 4F is a section in elevation of the heel area of the mid-soleof FIG. 4A-C along the lines 4F-4F of FIG. 4A;

[0027]FIG. 5A is a plan view of the upper surface of the inner-solewhich is supported by the mid-sole of FIGS. 4A-F;

[0028]FIG. 5B is a side elevation of the inner-sole of FIG. 5A whichshows a flange extending laterally from the upper surface;

[0029]FIG. 5C is a bottom view of the inner-sole of FIGS. 5A and 5B;

[0030]FIG. 5D is a section in side elevation of the inner-sole of FIG.5A-C along the lines 5D-5D in FIG. 5A;

[0031]FIG. 5E is a section in front elevation at the arch area of theinner-sole of FIGS. 5A-C along the lines 5E-5E of FIG. 5A;

[0032]FIG. 5F is a section in front elevation of the heel area of theinner-sole of FIG. 5A-C along the lines 5F-5F of FIG. 5A;

[0033]FIG. 6A is a cross sectional representation in elevation throughthe heel area of the combined in-sole/mid-sole showing the position ofthe mid-sole below and the in-sole above before the weight of a foot isimposed upon the in-sole;

[0034]FIG. 6B is a combination mid-sole and in-sole of 6A after theweight of a patient's foot has been imposed upon the in-sole of FIG. 6A;

[0035]FIG. 7A is a representation in elevation showing the heel area ofa patient's foot standing on a flat hard surface;

[0036]FIG. 7B is a schematic representation showing the parabolic natureof the high peak unit pressures generated by weight imposed upon thepatient's heel to support the weight;

[0037]FIG. 8A is a cross sectional representation in elevation of theheel area of a patient standing in a total contact cast with the foamlayer collapsed;

[0038]FIG. 8B is a schematic representation of the improved but stillparabolic nature of the peak unit pressures produced in the heel area bythe total contact cast in response to loading of the foot;

[0039]FIG. 9A illustrates a cross section elevation in the heel area ofthe improved walking boot of the present invention showing how part ofthe load is supported on the sides of the in-sole/mid-sole combinationin addition to the support provided to the bottom of the foot;

[0040]FIG. 9B is a schematic representation of the forces imposed on thepatient's foot in support thereof by the improved walker boot of FIG. 9Awherein the load is supported over a greater area without parabolicpeaks;

[0041]FIG. 10 is an outline of a person's foot indicating the amount ofsupported area when the foot is supported in different ways;

[0042]FIG. 11 is a graphical representation of the data from Table IIshowing that the average peak pressure on the plantar surface of thefoot is lower with the present invention than the next best prior artalternative;

[0043]FIG. 12 shows a grid of average peak pressure measurements for apatient wearing an ordinary shoe;

[0044]FIG. 13 is a grid of average peak pressure measurements for thesame patient using the Total Contact Cast;

[0045]FIG. 14 is a grid of average peak pressure measurements for thesame patient showing lower peak pressures with the improved walker bootof the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0046] In the description that follows, the improved walking boot fordiabetic and other patients of the invention, is designated generally bythe reference numeral 10. Throughout the description that follows, thesame reference numerals will be applied to similar parts. Referencenumerals with primes represent similar structure not exactly the same.

[0047]FIGS. 1 and 2 illustrate the combination of a walking shellgenerally designated 12 and what is referred to as a protective “bootie”generally designated by the reference numeral 14. This is more clearlyseen in FIG. 2 where they are separated. FIG. 1 illustrates acombination in use on a patient's leg and foot 16 which will be referredto as foot 16.

[0048] Walking shell 12 in FIGS. 1 and 2 has an inner surface 18 and anouter surface 20 to which is attached a walking tread 22 preferably madeof elastomeric material such as rubber. The shell is preferably bentslightly upwardly at what will be called a “rocker” line 24 whichimproves walkability of the structure when the patient moves forward.The tread follows the shape of the shell in this regard. An angled heelon the tread and an angled front greatly improve walkability.

[0049] Inner surface 18 of the walking shell comprises a foot bed in theshell designed to receive and support a mid-sole 28 which is seen inmore detail in FIGS. 4A-4F. The mid-sole has a lower outer surface 30which is supported by the inner surface 18 of walking shell 12. Walkingshell 12 has upwardly turned edges 32 in the heel area, edges 32′ in theside foot area and 32″ in the forefoot area. Although they need not besymmetrical, it is preferred that the upturned edges be generally thesame on both sides. The lower outer surface of 30 of mid-sole 28 hasupwardly rising side portions 34 at the heel, 34′ at the sides of thefoot and 34″ in the forefoot area which correspond to the upwardlyturned edges 32, 32′ and 32″ of the walker shell. These surfaces conformwith each other to provide firm unmoving support for the mid-sole.Additionally, it may be desirable to secure by means of adhesive or tapewith adhesive, the lower outer surface of the mid-sole 28 to the uppersurface or surfaces of foot bed 26.

[0050] Walker shell 12 further includes a flange 36 which is preferablyformed as an extension of the sides 32′ on each side of the shell.Attached to each one of the flanges 36 is an upright strut 38 comprisinga pair of upright struts 38. The upright struts 38 are attached to theflanges 36 by means of fasteners 39 best seen in FIGS. 3A and 3B. Eachstrut 38 is preferably covered with a cloth sheath 62 (attachment means)which is provided with spaced apart patches of hook and loop material 40which are used to removably attach bootie 14 as seen in FIG. 1.Attachment straps 64 have hook and loop material on their underside toengage hook and loop material 40 on the sheath 62 covering the struts toencircle and secure the entire walking boot assembly to the lower legand foot 16. The outer surface of second back portion 58 has patches ofhook and loop material to engage corresponding patches of hook and loopmaterial 40 on the inside of the sheaths 62 as well as seen in FIGS. 1and 3B. These constitute means for removably attaching booties 14containing the lower leg and foot to the walker shell 12. Buckles 42,preferably two on each side of the shell are fastened to the shell.Fastening means include a pair of straps 44 also having hook and loopmaterial 46 at appropriate locations. These straps 44 strap over thebootie and foot to hold the walker shell and bootie 14 components inplace.

[0051] Protective bootie 14 is best seen in FIGS. 1 and 2. Bootie 14 ismade with soft flexible spongy foam material which preferably breathesto some extent when it is wrapped around and secured to cushion thepatient's foot. Bootie 14 has a toe box 48, a tongue 50, side panels 52,a first back portion 54 and a second back portion 58. An inner-solegenerally indicated by the reference numeral 60 is seen forming thebottom of bootie 14 on which the sole of the foot will rest.Appropriately placed hook and loop material 62 is fastened to the bootieat appropriate places which makes it possible to enclose the injuredfoot within the bootie as shown in FIG. 1.

[0052] The foot is placed in bootie 14 and the open flaps 52 are crossedover the tongue 50 and fastened with hook and loop material 62. Thesecond back portion is wrapped around the lower leg and heel and alsofastened with hook and loop material 62. The foot and bootie are placedin the shell and the straps 44 are passed over the overlapping sideportions and tongue of bootie 14 where they are secured by hook and loopmaterial 46.

[0053] An improved supporting platform for the bottom of the feet isprovided by the combination of a pre-molded mid-sole illustrate in FIGS.4A-4F and a self-molding inner-sole illustrated in FIGS. 5A-5F. In FIGS.4A-4F, mid-sole 28 is pre-molded to have a lower outer surface adaptedto be received in the foot bed of the walker shell and an upper surface66 raised above the lower surface 30 and having a foot shaped cavitygenerally designated 68. Foot-shaped cavity 68 has a bottom surface 70spaced below upper surface 66. Mid-sole 28 is formed, preferably in onestructure, from a material having the characteristic that it willrebound from pressure force imposed by a foot and will not take acompression set, thereby essentially retaining its pre-molded shapeafter use. Yet it is flexible and will yieldingly deform to a limiteddegree when loaded by a foot. Most significantly, the foot shaped cavity68 has upwardly and preferably outwardly curving sides which rise to afoot shaped opening 72 at upper surface 66. Foot shaped cavity 68 hasupwardly curving side walls 74 around the heel area, upwardly curvingside walls 76 along the sides of the foot in the mid-foot area andupwardly curving side walls 78 in the forefoot area. The upwardlycurving walls at any given elevation generally lie parallel the footshaped opening 72. Also provided is an arch support area 80 which risessmoothly from the bottom in the normal manner of arch supports. Thecontour lines “C” in FIG. 4A are meant to indicate changes in elevationmuch as in a topographical map. It should be noted that this depressedarea which comprises the foot shaped cavity 68 is fairly deep,especially at the heel area and in the vicinity of the front of themid-foot where the ball of the foot will be placed. The depth may rangefrom approximately ¾ inch to as much as approximately 1 inch in thedeepest areas. The exact depth and size of the foot-shaped cavity islargely a matter requiring some experimentation to obtain the bestresults.

[0054] With the foot shaped cavity about the same or slightly largerthan the outline of a foot, the unique pre-molded cavity providesperipheral side edge support for the foot during standing or walkingwhich is superior to any form of flat bed or contoured flat surface andreduces “peak pressure” on any particular area of the bottom of thefoot. Peak pressure is meant to indicate the maximum unit pressureapplied to any given portion of the foot while walking in the bootstructure. Part of the load is spread around the sides of the footrather than just being supported on the bottom of the foot, as is thecase when the foot is placed on a flat surface. When the foot is placedon a flat surface, peak pressures can be expected mainly under the heeland ball of the foot where forces from the foot bones are primarilyapplied and where there is a minimum of protection underneath the boneyprojections in those areas in the form of flesh, muscle and fattytissue. The exact shape and curvature of the walls in the foot shapedcavity is largely a matter of trial and error and subject to thedifficulty that feet do not come in a standard uniform shape or size.Nevertheless, the basic principle of providing a foot shaped cavity withsloping walls has been shown to reduce the maximum or peak unit pressureand the average unit pressure over the best alternative currentlyavailable, namely the Total Contact Cast. Because there are differencesin shape and size of feet, the mid-sole of the invention is preferablyused in combination with an inner-sole 60 having generally a foot shapedoutline but having quite different characteristics.

[0055] Inner-sole 60 is illustrated in FIGS. 5A-5F. The combination ofinner-sole 60 and mid-sole 28 is illustrated in FIGS. 6A and 6B.Referring now to FIGS. 5A-C, inner-sole 60 has a foot receiving uppersurface 82 and a lower outer surface 84 comprising a bottom surfaceadapted to fit over upper surface 66 of mid-sole 28, especially over thefoot-shaped cavity 68. Upper surface 82 of inner-sole 60 preferably hasa slightly depressed contoured upper surface as indicated in FIGS.5D-5F. This is largely a matter of feel and comfort which help centerthe foot. The bottom surface or underside 84 is also contoured asindicated by the contour lines C in FIG. 5C. A raised contoured archarea 86 may be included for comfort, better fit and arch support. Aperipheral flange 88 is preferably provided all around the inner-sole.The peripheral flange is useful for securing the inner-sole againstmovement and provides a convenient means of attachment to bootie 14 asindicated in FIG. 2A by sewing, adhesive or other means.

[0056] Inner-sole 60 is preferably formed in one piece from a materialhaving a self-molding characteristic in response to pressure from afoot. It is a spongy preferably foam material having the characteristicthat it does not readily rebound from pressure force and will take acompression set in response to foot pressure. The material shouldcompress readily for more than half of its thickness before it begins tosignificantly resist further compression caused by the foot. Inner-sole60 preferably is molded from an elastomeric foam material having askinned outer surface to prevent absorbing fluids from ulcerated areasof a patient's foot. Because the inner-sole can be cleaned, it does notrequire discarding after a period of use by a patient as does the TotalContact Cast.

[0057]FIGS. 6A and 6B illustrate how the mid-sole 28 and inner-sole 60work together to distribute foot loading to the boot shell over agreater peripheral area of the foot. These are simplified diagrams whichexclude all the other components of the walking boot of FIG. 1 forpurposes of clarity. For purposes of illustration, these may beconsidered cross sections through the heel area of FIG. 4F and FIG. 5F,although the same advantage is observed around the rest of the foot.

[0058]FIG. 6A illustrates the initial condition before the materialshave been subject to foot pressure. In FIG. 6B, inner-sole 60 has beenself-molded by exposure to foot pressure and compressed to a significantdegree, especially in the bottom area 90 of FIG. 6B. The side wall areas92, 94 have been compressed also, but to a lesser extent than the bottom90, as compared to the original thickness of inner-sole 60. Althoughinner-sole 60 in its compressed configuration remains flexible andretains some compressibility, it is essentially compression set. It doesnot return to its original shape when the foot is removed whereasmid-sole material 28 always returns essentially to its initial shapewhen force imposed by the foot is removed. The result is an alteredfoot-shaped cavity 68′ which has been self-molded by the foot to formupwardly and outwardly curving side walls 92, 94 around the heel andother sides of the foot. Pressure from the foot has caused theinner-sole to mold itself closely to the foot and tightly against theupwardly and outwardly curving walls of mid-sole 28. It can be seen thatthe load imposed on the foot by the weight of the person is notconcentrated only on bottom 90 but is also partially resisted by theside portions 92, 94 because the shape and thickness of the material isselected so that the outer peripheral edges of the foot come in contactwith the side walls of the foot-shaped cavity 68′ before the footbottoms out at the bottom 90. It should also be noted that the crosssectional thickness 96 of mid-sole 28 is selected to be a lesserthickness under those parts of the foot having boney protrubences, herethe heel, thereby minimizing leg height differential and any relativemotion between the foot and the sides of the foot-shaped cavity 68′which is supporting the foot, which could otherwise be caused byperiodic compression of the mid-sole in response to foot loading whilewalking.

[0059]FIGS. 7A, 8A and 9A schematically represent various supportingstructures which might be considered as being in the nature of verticalcross sections through the heel portion of a supporting structure inFIGS. 8A and 9A. FIGS. 7B, 8B and 9B are schematic representations ofthe force distribution acting on the supported portion of the heel. Themagnitude of the force is indicated by the length of the arrows.

[0060]FIG. 7A illustrates the foot 16 supported on a board 96. This is acondition which would be experienced walking on a hard surface in barefeet. The heel bone is not far under the surface of the skin and fleshypadding. Although the fleshy padding is able to distribute the weight tosome extent, the distribution of weight is limited and a fairly highpattern of peak forces 98 support the weight over a limited area. Theforces vary, of course, from zero when the foot is in the air to amaximum when the heel comes down and the weight of the body is rolledover it. FIGS. 7B-9B are meant to indicate the maximum forcedistribution on the foot which occurs while walking or standing. In FIG.7B, this maximum force is distributed over an area 100 which exhibitswhat we call a parabolic force distribution. The forces are highest inthe center and drop off rapidly near the edges.

[0061]FIG. 8A schematically represents the Total Contact Cast 102. Thecast material itself is material such as plaster of paris or a syntheticcross linked polymer mixture. Not all of the layers of wrapping areshown here under the cast, but one possible feature that is shown is theelastomeric foam material 104. The board 96 is shown as it is usually acomponent of the Total Contact Cast. It can be seen that the supportedarea 106 is significantly larger than the area 100 of FIG. 7. The peakforces 108 are significantly smaller than are in FIG. 7B but they stillhave what we refer to as a parabolic shape with the highest forcesapplied to the lowermost boney parts of the foot. Most of the supportingforce is in the center and falls off rapidly to each edge.

[0062]FIGS. 9A and 9B represent the improved walking boot 10 of theinvention. FIG. 9A shows the unyielding walking shell 12 having a tread22, closely supporting mid-sole 28 and preventing it from spreadingoutward. Inner-sole 60 has been substantially compressed by the weightof the foot to the point where it provides substantial resistance tofurther compression. Because the foot is “wedged” into the foot shapedcavity 68′, the force to support the weight on the foot is distributedover a significantly larger area 110 and the resulting peak forces 112in FIG. 9B are measurably less than FIG. 8B. Since the Total ContactCast of FIG. 8A is the best known prior art structure, this means theimprove walking boot of the invention represents an advance in the artof Orthopedic devices.

[0063]FIG. 10 is an orthotic of a person's foot indicating schematicallythe amount of supported area when the foot is supported in differentways. The area 120 might be the imprint of a damp bare foot on dryconcrete. With a normal arch, the weight is distributed over arelatively small area compared to the area of the bottom of the boot.The area 122 is believed to be the kind of supported area that acontoured but generally flat and somewhat resilient walker orthoticin-sole might provide. There is more supported area to reduce unitpressure imposed on the bottom of the foot, but the supported area isstill significantly less than the total available area. The dotted area124 is meant to symbolize the amount of supported area that can beprovided by the invention. Because part of the support for the footcomes from the peripheral areas of the foot, the foot load is spreadover a still greater area with resulting lower unit pressure at anygiven location around or on the bottom of the foot.

[0064] A way has been found to measure plantar pressures under the footusing the Novel Pedar in-shoe pressure measurement system made by Novelof Dusseldorf, Germany. The Novel system has an insert which looks likethe inner-sole in a shoe and is shaped like a foot so it will fit rightinto a shoe. The in-shoe sensor has an upper grid and a lower gridseparated by a layer of silicone with a vinyl layer on the top andbottom of the in-shoe pressure measurement device. The grids form aplurality of little squares distributed regularly over the area of thein-shoe pressure measurement device. Conductors representing each of thelittle sensor squares are connected to a programmed computer whichmeasures changes in capacitance that occur when the grids are movedcloser to each other in response to pressure forces. The device isapproximately 2 mm thick with approximately 99 sensors per insole androughly 1 sensor per square centimeter depending upon the insole size.The Novel Pedar in-shoe pressure measurement device is calibrated bymeans of a diaphragm using a known air pressure to push down on theinsole. Very low pressures below about 1 or 2 newtons per centimetersquare are treated by the software as zero pressure.

[0065] A series of comparisons were made using the Novel device tocompare the performance of the best available orthopedic device, theTotal Contact Cast, with the improved walking boot of the invention.Eighteen normal subjects without any prior foot or ankle problems wereemployed in this study. There were 7 females and 11 males in the studywith an average weight of 85.6 kilograms and an average height of 177centimeters. Data on these 18 subjects is given Table 1 below. Theresults of the tests are given in Table II and displayed graphically inFIG. 11. TABLE 1 SUBJECT AGE WEIGHT HEIGHT Sub 1 27.0 82.7 182.9 Sub 246.0 86.4 182.9 Sub 3 34.0 77.3 170.0 Sub 4 27.0 62.7 154.0 Sub 5 33.087.3 190.3 Sub 6 49.0 75.0 177.8 Sub 7 27.0 47.7 154.9 Sub 8 45.0 115.9193.0 Sub 9 49.0 125.0 190.5 Sub 10 39.0 100.0 188.0 Sub 11 66.0 113.6190.5 Sub 12 38.0 117.3 162.6 Sub 13 21.0 95.5 170.2 Sub 14 34.0 66.4177.8 Sub 15 27.0 63.6 167.6 Sub 16 35.0 86.4 188.0 Sub 17 26.0 65.9162.6 Sub 18 46.0 72.7 172.7 average 37.2 85.6 176.5 standard dev. 11.321.9 12.7

[0066] The present invention has been given the name Bledsoe ConformerDiabetic Boot or “Boot”. Each subject was asked to walk 1.) in theBledsoe Conformer Diabetic Boot and 2.) in a well-padded Total ContactCast which is also referred to as a short leg cast. The Total ContactCasts were all administered by the same casting technician using thesame techniques applied by the Baylor University Medical Center, Dallas,Tex. to treat diabetic ulcers. The subjects were randomly assigned tothe order of testing for the two conditions and asked to walk severaltimes at a self-selected speed down a ten-meter walkway. Approximately15 steps for each condition were used for averaging and statisticalanalysis. Paired t-tests were used to compare between the short leg castresults and the boot results at an alpha level of 0.05 for thestatistical tests. The tests were naturally conducted over a period ofweeks because it takes a great deal of time and effort to prepare andapply the Total Contact Cast to the individual feet. Pressure maps ofeach Novel insole were divided into three regions called masks: heel,midfoot, and forefoot. The heel is generally the area from the back ofthe heel to the front of the heel, the midfoot is generally the areafrom the front of the heel to the ball of the foot, and the forefoot isthe area from the ball of the foot to the toes. Each mask area includeda certain number of the sensor squares.

[0067] Although a number of different measurements were made, peakplantar pressure is considered to be most significant to the diabeticulceration problem because of theories that below a certain peak plantarpressure new ulcers will not form and ulcers already formed will heal.TABLE II PEAK PRESSURE - N/cm² TOTAL HEEL MIDFOOT FOREFOOT SUBJECT BOOTCAST BOOT CAST BOOT CAST BOOT CAST Sub 1 15.2 23.3 14.3 16.0 8.1 7.913.6 23.0 Sub 2 10.7 19.1 9.6 12.5 5.2 10.3 10.5 19.1 Sub 3 14.3 22.312.9 14.5 5.3 8.7 14.3 22.3 Sub 4 11.9 12.9 9.2 12.6 3.9 5.3 11.8 8.5Sub 5 14.2 21.7 12.9 16.6 5.6 11.6 13.3 21.6 Sub 6 9.9 22.6 7.8 9.1 7.54.0 8.5 22.6 Sub 7 13.7 14.5 12.6 11.8 7.2 8.0 12.8 14.2 Sub 8 19.7 26.811.6 26.1 4.9 12.7 18.9 23.8 Sub 9 13.2 21.0 9.5 17.0 3.2 10.5 13.2 20.8Sub 10 11.3 20.5 9.6 16.3 2.7 11.6 11.2 19.1 Sub 11 20.5 24.1 20.5 16.39.7 16.3 11.6 23.8 Sub 12 12.9 18.3 11.6 6.0 8.9 8.1 11.9 18.3 Sub 1313.7 20.3 13.7 10.2 8.6 9.8 9.7 20.3 Sub 14 13.5 14.8 12.6 12.9 10.2 5.812.2 14.0 Sub 15 13.8 20.2 12.8 20.2 3.7 6.5 9.8 9.6 Sub 16 18.4 21.918.4 21.9 6.1 9.0 8.1 10.6 Sub 17 14.5 15.6 13.2 12.9 13.2 9.6 9.3 15.2Sub 18 10.0 12.5 9.9 8.5 9.6 5.1 4.6 11.1 average 14.0 19.6 12.4 14.56.9 8.9 11.4 17.7 stdev 2.9 3.9 3.1 4.8 2.8 3.1 3.0 5.2 T-test 0.000000.07730 0.05910 0.00002

[0068] Table II has four columns containing comparative data for eachsubject wearing the boot and the cast. The data is paired and given interms of newtons of force per centimeter squared. The left hand columngives the peak pressure in newtons per centimeter square that was foundanywhere on the foot. The other three columns from left to right givethe peak pressure respectively in the heel, midfoot and forefoot areafor each of the Bledsoe Conformer Boot and the Total Contact Cast.Averages and standard deviations were calculated for each column ofdata. In each case the average peak pressure for the boot was lower thanthe average peak pressure for the Total Contact Cast in every area ofthe foot. The difference was considered to be statistically significantin at least the midfoot and forefoot areas in this test and in anothertest was considered to be statistically significant in each of the heel,midfoot and forefoot areas. The cross bar and stem sitting on top thevertical data bars in FIG. 11, as indicated by asterisks 118, are meantto represent the scope of the range of the data contained within thedata bar. This is true for all data bars.

[0069]FIGS. 12, 13 and 14 show representations of the sensor quadrantsfor a single patient wearing the shoe, the Total Contact Cast and theBledsoe Conformer Boot. Each of the small squares can be considered apressure sensor of the Novel Pedar in-sole sensing device. A grid ofnumbers at the left and above identify the sensor squares. A graphicalcode for the pressure reading is given on the right hand side of eachchart in newtons per square centimeter. The values are indicated asbeing greater than or equal to the number corresponding to the graphicalcode. While the scale shown only goes up to 30 newtons per squarecentimeter, it should be understood that some of these values actuallywent up to a figure of 60 newtons per centimeter squared but this wasnot reflected in the charts. The heel in these charts is on the lefthand side of the chart. A blank area in the shoe chart indicates afailure of the sensors to record a pressure value.

[0070] What is significant about these charts is that they illustratethe difficulty of the problem because of the varying contours of theplantar surface of the foot and the boney projections which distributeweight nonuniformly and in fact create “hot” spots. In the shoe exampleof FIG. 12 it can be seen that there is an area of high pressure inexcess of 30 newtons per square centimeter which appears to be near thebig toe area. There are pressures in excess of 22 newtons per squarecentimeter in the area of the ball of the foot. The Total Contact Castof FIG. 13 exhibits lower pressures overall but there are still someareas in excess of 22 newtons per square centimeter. In contrast, theBledsoe Conformer Boot in this example had no areas anywhere on the footthat were equal to or greater than 15 newtons per centimeter squared.

[0071] In the best mode, the walker shell is formed from aluminum sheetbecause it is lightweight and will bend should it be necessary to makeslight adjustments. The self-molding inner-sole is a closed celloff-white PVC foam from Saint-Gobain Performance Plastics Corporation,Granville, N.Y. under the designation HAFG 16 having an overallthickness of about ½ inch. The material has a density of about 7.5pounds per cubic feet and a hardness on the Shore 00 scale which is saidto be about 56. The material has the characteristic that it will readilycompress to less than half its thickness and if compressed to less thanhalf its thickness for a significant period of time by the foot, tendsto retain the compressed shape. It has a fairly flat increase indeflection before it begins to resist.

[0072] The mid-sole is preferably made from Bayflex® 904 obtained fromthe polymer division of Bayer Corporation. It is described as amicrocellular polyurethane foam system which was developed for use inapplications requiring a microcellular core and a toughabrasion-resistant outer surface. It is formulated to a “hardness” ofabout 65-75 on the Shore 00 scale.

[0073] Although the invention has been disclosed above with regard to aparticular and preferred embodiment, it is not intended to limit thescope of this invention. It will be appreciated that variousmodifications, alternatives, variation, etc., may be made withoutdeparting from the spirit and scope of the invention as defined in theappended claims.

What is claimed:
 1. An improved walking boot, comprising: a walkingshell having an inner and an outer surface wherein the outer surface isa walking surface and the inner surface is a foot bed designed toreceive and support a mid-sole; a premolded mid-sole having a lowerouter surface mounted on the foot bed, the mid-sole having an uppersurface comprising a foot shaped cavity having a bottom surface withupwardly curving sides which rise to a foot shaped opening; aninner-sole having a foot receiving upper surface and a bottom surfaceadapted to fit over the upper surface of the mid-sole, the inner-solehaving a self-molding characteristic in response to pressure from a footthat allows the inner-sole to mold itself closely to a foot and tightlyagainst the upwardly curving walls of the mid-sole; and whereby supportfor a foot is provided around the heel and sides of the foot as well asunder the foot.
 2. An improved walking boot according to claim 1,wherein: the mid-sole has a lower outer surface, which is supported bythe inner surface of the walking shell to prevent spreading of themid-sole by contact between the mid-sole and the inner surface of thewalking shell in response to foot pressure.
 3. An improved walking bootaccording to claim 2, wherein: the walking shell has upwardly turnededges along at least the sides and heel areas which provide support tothe lower outer surface of the mid-sole to prevent spreading of themid-sole.
 4. An improved walking boot according to claim 2, wherein: themid-sole is secured to the walking shell against sliding of the mid-solerelative to the walking shell.
 5. An improved walking boot according toclaim 1 wherein the inner-sole is secured to the mid-sole in a mannerthat prevents shifting movement.
 6. An improved walking boot accordingto claim 1, wherein: the inner-sole has a peripheral flange extendinglaterally substantially all around the foot shaped opening; and adurable and resilient soft support comprising a protective bootie forextending around the lower leg and foot wherein the bootie has an openbottom having bottom edges secured to the peripheral flange of theinner-sole to restrict hard foreign objects from reaching the foot. 7.An improved walking boot according to claim 1, wherein: the mid-sole isformed from material having the characteristic that it will rebound frompressure force and will not take a compression set; and the inner-soleis formed from a soft spongy material having the characteristic that itdoes not readily rebound from pressure force and will take a compressionset in response to foot pressure.
 8. An improved walking boot accordingto claim 7, wherein: the inner-sole comprises an elastomeric foammaterial having a skinned outer surface.
 9. An improved walking bootaccording to claim 1, wherein: the mid-sole is formed from materialhaving the characteristic that it will rebound from pressure force andwill not take a compression set thereby essentially retaining itspremolded shape after use.
 10. An improved walking boot according toclaim 8, wherein: the cross-sectional thickness of the mid-sole isselected to be a lesser thickness under those parts of the foot havingbony protrubences, as opposed to other boney parts of the foot cushionedwith more tissue, thereby minimizing leg height differential and anyrelative motion between the foot and sides of the foot shaped cavitysupporting the foot caused by periodic compression of the mid-sole inresponse to foot loading while walking.
 11. An improved walking bootaccording to claim 9, wherein: the foot shaped opening is nearly thesize of a selected average foot, but larger than the projected shape ofsaid foot onto a flat surface and wherein the size and shape of the footshaped cavity is selected so that the foot is preloaded along the sidesbefore the foot is loaded on the bottom.
 12. An improved walking bootaccording to claim 10, further including: a durable and resilient softprotective bootie secured to the inner-sole and extending around thelower leg and foot to protect the foot from injury and enclose the footto prevent extraneous particles of foreign material from entering thearea where the foot is protected.
 13. An improved walking boot accordingto claim 11, wherein: the walking shell has an outer lower surface whichis closely supported unyieldingly on the bottom and sides by thefoot-shaped bed of the walking shell to prevent spreading of themid-sole in response to foot pressure in the foot-shaped cavity.
 14. Animproved walking boot, comprising: a walking shell having an innersurface having an upturned edge portion which forms an unyieldingfoot-shaped bed adapted to support a mid-sole; a mid-sole supported inthe foot-shaped bed, the mid-sole having a foot-shaped cavity withrounded sides adapted to provide form resilient support for the heel andsides of a foot in addition to the bottom of a foot; a conformableinner-sole adapted to fit over the foot-shaped cavity in the mid-soleand be compressed in response to foot pressure between the sides andbottom of the foot and the sides and bottom of the foot-shaped cavity inthe mid-sole thereby compensating for small differences between theshape of the foot and the shape of the cavity; and whereby weightapplied to the foot is transferred to the walking shell by contactbetween the sides of the foot and heel and the sides of the foot-shapedcavity as well as the bottom of said cavity.
 15. The improved walkingboot of claim 14, wherein: the mid-sole has an outer lower surface whichis supported closely and unyieldingly on the bottom and sides by thefoot-shaped bed of the walking shell to prevent spreading of themid-sole in response to foot pressure in the foot shaped cavity.
 16. Theimproved walking boot of claim 15 wherein: the upturned edge portion andinner surface of the walking shell extends around the heel and sides ofthe foot shaped bed and wherein the lower outer surface of the mid-soleand the inner surface of the foot-shaped bed are surfaces conformingwith each other to provide firm unmoving support for the mid-sole. 17.The improved walking boot of claim 14 wherein: the mid-sole is premoldedwith the foot-shaped cavity, from material having the characteristicthat it will rebound from pressure force and will not take a compressionset thereby essentially retaining its premolded shape after use.
 18. Theimproved walking boot of claim 17 wherein: the cross-sectional thicknessof the mid-sole is selected to be a lesser thickness under those partsof the foot having bony protrubences, as opposed to other boney parts ofthe foot cushioned with more tissue, thereby minimizing leg heightdifferential and any relative motion between the foot and sides of thefoot shaped cavity supporting the foot caused by periodic compression ofthe mid-sole in response to foot loading while walking.
 19. The improvedwalking boot of claim 17, wherein: the foot shaped cavity has a footshaped opening nearly the size of a selected average foot, but largerthan the projected shape of said foot onto a flat surface and whereinthe size and shape of the foot shaped cavity and the thickness of theconformable inner-sole are selected so that the foot is preloaded alongthe sides before the foot is fully loaded on its bottom.
 20. Theimproved walking boot of claim 19 wherein the conformable inner-sole issecured to the mid-sole.
 21. The improved walking boot of claim 20wherein: the conformable inner-sole is secured to the mid-sole by meansof a peripheral flange which extends laterally outwardly relative to thefoot-shaped opening of the mid-sole.
 22. The improved walking boot ofclaim 21 further including a durable and resilient soft protectivebootie adapted for extending around the lower leg and foot and having anopen bottom portion having sides all around the foot that are secured tothe peripheral flange of the inner-sole to form a soft protective bootiearound the foot and lower leg.
 23. The improved walking boot of claim19, further including: a durable and resilient soft protective bootiesecured to the inner-sole and extending around the lower leg and foot toprotect the foot from injury and enclose the foot to prevent extraneousparticles of foreign material from entering the area where the foot isprotected.
 24. An improved walking boot, comprising: a walking shellhaving an inner surface having an upturned edge portion which forms anunyielding foot-shaped bed adapted to support a mid-sole; a mid-solesupported in the foot-shaped bed, the mid-sole being premolded to form afoot-shaped cavity with upwardly and outwardly rounded sides to form aresilient but non-compressively setting support for the sides of a heeland sides of a foot in addition to the bottom of a foot; a conformableinner-sole formed from pliable but compressibly settable materialwherein the conformable inner-sole is adapted to fit over thefoot-shaped cavity in the mid-sole and be compressed in response to footpressure between the sides and bottom of the foot and the sides andbottom of the foot-shaped cavity in the mid-sole thereby compensatingfor small differences between the shape of the foot and the shape of thefoot-shaped cavity; whereby weight applied to the foot compresses andmolds the conformable inner-sole to fit tightly between the heel andsides of the foot thereby preloading the foot along the heel and thesides of the foot before the foot is fully loaded by fully compressingthe inner-sole and the mid-sole at the bottom of the cavity.
 25. Animproved walking boot according the claim 24 wherein the foot-shapedcavity in the mid-sole has a foot-shaped opening near the size of aselected average foot and where the size and the shape of thefoot-shaped cavity and the thickness of the conformable inner-sole areselected to assure that the foot is preloaded along the sides of thefoot-shaped cavity before the foot is fully loaded on its bottom.
 26. Animproved walking boot according to claim 25 wherein the conformableinner-sole comprises an elastomeric foam having a skinned outer surfaceto prevent penetration by moisture or other liquids.
 27. An improvedwalking boot according to claim 25 wherein the cross sectional thicknessof the mid-sole in the highly loaded areas under the heel and ball ofthe foot are selected to be a minimum thickness in order to minimize legheight differential and any relative motion tending to be caused bycompression of the mid-sole, which might occur between the foot andsides of the foot-shaped cavity supporting the foot, arising because ofperiodic compression of the mid-sole in response to foot loading whilewalking.
 28. An improved walking boot according to claim 27 furtherincluding a durable and resilient soft protective bootie secured to theinner-sole and extending around the lower leg and foot to protect thefoot from injury and enclose the foot to prevent extraneous particles offoreign material from entering the area where the foot is protected. 29.The improved walking boot according to claim 28 wherein the mid-sole hasan outer lower surface which is closely supported unyieldingly on thebottom and sides by the foot-shaped bed of the walking shell to preventspreading of the mid-sole in response to foot pressure in thefoot-shaped cavity.
 30. The improved walking boot according to claim 29wherein the walking shell has a pair of upstanding struts which serve tosecure the walking boot and bootie on the leg of the wearer.
 31. Amethod of supporting an injured foot, comprising: providing a walkingshell having inner and outer surfaces wherein the outer surface is awalking surface and the inner surface is a foot bed designed to receiveand support a mid-sole; mounting a premolded mid-sole in the foot-bed,the mid-sole having a foot shaped cavity having a bottom surface withupwardly curving sides which rise to a foot shaped opening; placing aself-molding inner-sole having a foot receiving upper surface and abottom surface adapted to fit over the upper surface of the mid-sole ina manner that allows the inner-sole to conform itself closely to a footand fit tightly against the upwardly curving walls of the mid-sole;placing a foot on the foot receiving upper surface of the self-moldinginner-sole over the foot receiving cavity in the mid-sole; and puttingweight on the foot, thereby conforming and compressing the self-moldinginner-sole closely against the foot between the bottom and sides of thefoot and the foot-shaped cavity to shift some of the weight to the sideportions of the foot before the bottom of the foot is loaded, therebyminimizing unit pressure applied to the foot.
 32. The method of claim31, wherein: the step of providing a walking shell having a foot bed andmounting a premolded mid-sole in the foot bed are accomplished byproviding conforming mating surfaces where the mid-sole contacts thefoot bed; and the step of putting weight on the foot is not accompaniedby the step of spreading the mid-sole outwardly in response to theweight.
 33. The method of claim 32, wherein: the step of mounting apremolded mid-sole in the foot-bed comprises includes the step ofproviding a mid-sole prepared from a material having the characteristicof yielding without taking a compression set; and the step of puttingweight on the foot is accompanied by the step of some non-permanentyielding of the mid-sole which is substantially less than thecompression of the self-molding inner-sole in conforming to the foot inresponse to loading applied to the inner-sole by the foot.
 34. Themethod of claim 33 further comprising the step of surrounding the lowerleg and foot with a durable and resilient soft protective bootie. 35.The method of claim 34 further including the step of protecting the footfrom hard foreign particles which may be encountered when walking bysecuring the self-molding inner-sole to the bottom portion of theprotective bootie.